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How The Motor Dampers Work

The motor dampers are just a component that uses different damping effects in different places or in different working environments. Damper: for damping; Snubber: for shock, low speed allows to move, when the speed or acceleration exceeds the corresponding value of the lock, the formation of rigid support.

Various applications include: spring motor dampers, hydraulic motor dampers, pulse motor dampers, rotating motor dampers, wind turbine dampers, viscous motor dampers, damping hinges, damping slides, furniture hardware, cabinet hardware The


High-speed rotating machine vibration problem is a more prominent and difficult to solve the problem. The speed of this machine is high, all in the critical and even higher than the critical speed to run. Therefore, in order to ensure its safe operation, in addition to ensuring careful design and accurate manufacturing installation, AC Motor Damper usually also use the motor damper to reduce vibration. Squeeze film motor dampers and electromagnetic motor dampers are two commonly used motor dampers. This paper designs a new type of controllable passive electromagnetic motor damper.

Structure and working principle of controllable passive electromagnetic motor dampers

Figure 1 is a schematic diagram of a controllable passive electromagnetic motor damper. It has no displacement sensor. The structure is similar to the extruded oil film motor damper: the rotor (1) of the rotating machine is supported on the core (3) by means of a rolling bearing (2) or a sliding bearing. AC Motor Damper The core is further supported on the base (5) by means of a spring (4). The stiffness of the spring can be designed according to the requirements of the use, to support the main stiffness of the system. In the base around the core concentric placed four electromagnets (6). Each of the magnet coils are acting on the same size of the DC excitation voltage.

Figure 2 shows the controllable passive electromagnetic motor damper generated by the additional stiffness and damping with the frequency of the situation. AC Motor Damper It can be seen that the value of the additional stiffness over the entire frequency range is negative and the negative stiffness value decreases as the frequency increases. The stiffness value in the high frequency region is almost zero. This damping characteristic just conforms to the low frequency damping high frequency small damping required by the rotating machine. After the dimensions of the controllable passive electromagnet dampers are determined, the stiffness and damping values depend only on the static excitation current or the excitation voltage. Changing the excitation voltage can change the stiffness and damping, AC Motor Damper so this motor damper is controllable.

experimental device

Figure 3a is an experimental device: an elongated shaft, one end supported on a conventional rigid ball bearing and the other end supported on the electromagnetic motor damper support shown in Fig. The rotor is driven by a DC motor. The vibration and rotational speed of the shaft are detected by the eddy current sensor and the photoelectric sensor respectively. The vibration signal and the speed signal are collected by the computer through the AD board. Figure 3b is a plate radial spring providing a primary bearing stiffness. AC Motor Damper The spring is made of elastic aluminum as a material. The stiffness values are calculated and optimized by finite element. There are two springs placed side by side on an electromagnetic motor damper support to ensure symmetry and to facilitate system modeling. Theoretical calculations and experimental tests show that the first critical speed of the rotor is about 3900revs / min.


The vibration of the rotor with the speed is measured at different excitation voltages. Figure 4 shows the experimental data. The four curves in the figure represent the case where the excitation voltages are 0 volts, 9 volts, 12 volts, and 15 volts, respectively. It can be seen that the damping provided by the electromagnetic motor dampers increases as the field voltage increases. AC Motor Damper This makes the amplitude of the rotor be suppressed, from 0.185mm down to 0.56mm, damping effect is very obvious. It can also be seen from the figure that the critical speed of the rotor is reduced due to the presence of negative electromagnetic stiffness. This is consistent with the results in Figure 2, near the critical speed of 65HZ, the additional negative stiffness of the electromagnetic force and its impact on the critical speed is very small. When the excitation voltage is 15 volts, the critical speed of the rotor only drops to 3780revs / min.

in conclusion

Passive electromagnetic motor dampers for the rotor system to achieve a better damping effect. The damping mechanism of this motor damper is passive and the size of the damping is controlled by the magnitude of the excitation voltage. Compared with the extruded oil film motor damper, the passive electromagnetic motor dampers have the most advantages of the electromagnetic bearing relative to the ordinary bearing. Compared with the active electromagnetic motor dampers, the passive structure of the passive electromagnetic motor dampers is simple and the cost is low, More reliable. So this is a promising and promising high-speed rotor damping device.